Vacuum Tube Current Sync Drive; Why Tubes; Vtcsd - US Amps AX Installation Manual

Why Tubes?

You may know that a transistor is a
modern, efficient, less expensive version of
a vacuum tube, which is the device that made
sound recording and reproduction possible in the
first place. Now, the electronics industry has been
trying for many years to equal the sound quality available from tubes. They have
been able to make transistor amps louder, cooler, more abusable, and less expen-
sive than tubes, but to this day, they've been unable to make any solid state amp
sound as good as a tube amp.
So, our engineer got to wondering, "What if I combined the sonic character of a
vacuum tube with the drive capabilities of solid state?"
Well, the result is the U.S.Amps' VTCSD hybrid amps. Using the signal path
directly out of the tubes as a "steering" signal and the following drive signal wave
from the transistors as the "motor," with absolutely no negative feedback as a
corrective to the transistor's waveform, we achieved the most detailed, pleasing,
articulated sound available in mobile audio today.
Tube In, Tube Out

VTCSD

Hybrid Tube/Transistor Amps
Solid State Input
Low Voltage
Low Current
Classic Vacuum Tube Amps w/Output Transformer
Tube Input
Low Voltage
Low Current

Vacuum Tube Current Sync Drive

Direct Input
Input signal is fed
DIRECTLY into the tube.
There are no solid state
gain stages or processors
in the signal path.
(Vacuum Tube Current Sync Drive)
Solid State Amplifier
Preamp Signal
Smooth, Low
Negative Feedback
Tube Voltage
Transistor Switching
High Voltage/Low Current
Signal from Output Tube is
fed into Output
Transformer
Positive Current Sync
Negative Current Sync
Uneven Clipping
Odd-order Harmonics
Listening Fatigue
Compression
Noise
and Coloration
The resultant signal
is soothing and
Output
pleasing
Transformer
converts
Voltage
Energy
into
Yet lacks much of
Current
the tubes' original
dynamic range
The original high voltage tube signal is joined by
a null-gain current following circuit that is pulled
to the voltage rails by an opposing pair of
current syncs, providing a sort of amplifier
"power steering" to deliver speaker-driving
power without taxing the character of the
original tube voltage content.
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